1. Field of the Invention
The present invention relates to a cap for a vessel, particularly to an effective technology to be applied to a cap of a bottle for a medical fluid such as a so-called vial.
2. Related Art Statement
Generally, a typical example employed as a bottle for a medical fluid is a flip-off cap, a pull-top cap or a clean cap, so called.
Of these, there are the following problems in the case of a flip-off cap (cf., e.g., Japanese Utility Model Laid-Open No. 52-52853):
(a) it has a joint structure of a molded resin and pressed aluminum, and thus the cost thereof is high,
(b) it is difficult to keep sanitary quality because an alien matter such as a hair tends to be caught in the joint portion, and, moreover,
(c) breaking the seal of the cap is carried out by a fingertip, and thus, in such a case as in a hospital where a great amount of bottles are to be opened, the fingertip tends to be damaged, and much time is required to open them.
While, there are also many problems in the case of a pull-top cap:
(a) it should be opened with both hands, and thus it is inconvenient, and particularly, much time is required where a great amount of the caps are used,
(b) a clip of the cap should be pulled upwardly with much force on breaking the seal, and thus much labor is required for the operations, and
(c) a finger or the like tends to be injured by the clip after the seal breaking.
In contrast to these caps, in the case of a clean cap, the seal breaking can be done only by pushing a projection of the cap, and thus it is superb in an operational sense and convenient even when used in large quantities.
However, there also remain the following problems in the case of this structure.
That is, in the structure as disclosed in, e.g., Japanese Patent Laid-Open No. 58-1662, the lower end of the cap has a split for the removal, and when the cap is removed, a rubber stopper sealing an opening of a bottle is also removed together. Accordingly, there remain the following serious defects:
(a) once it is opened, alien matters tend to enter therein from the opening, and thus it is difficult to keep the sterility, and
(b) it can be used only once because preservation of contents is difficult. Thus it is not usable in a brick test or the like where subdivision is required.
Hereupon, there is disclosed, in Japanese Utility Model Laid-Open No. 59-89855, a cup structure in which a plurality of through holes are formed in series around the base portion of a projection provided at the top side of a cap, and the projection can be removed by bending it at the portion of the through holes.
However, by this cap structure, the opening edge of the cap after removing the projection by bending becomes a sharp jagged edge owing to the alternate combination of the formed portions of the through holes and non-formed portions thereof, so that when the projection is removed by pushing and bending it with, e.g., a tip of thumb, the palm side (inside) of the thumb tends to be injured by touching the jagged edge.
Thus, there remain problems that the cap is dangerous on the seal breaking operation thereof, and inferior in its operational property.
Moreover, there also remains a serious problem that because a plurality of the through holes are formed at the top side of the cap, alien matters such as minute dust tend to enter from the through holes during preservation, and the space between the inner side of the cap and the rubber stopper is contaminated before opening.